Generally speaking, in a clutch unit using engagement elements such as cylindrical rollers or balls, a clutch portion is arranged between an input-side member and an output-side member, and, in the clutch portion, the engagement elements such as cylindrical rollers or balls are engaged/disengaged with respect to wedge gaps formed between the input-side member and the output-side member, thereby controlling transmission/interruption of the input torque.
A clutch unit of this type is incorporated into an automobile seat-lifter section for an which vertically moves a seat with lever operation. This clutch unit is provided with a lever-side clutch portion transmitting rotational torque from the input side to the output side and a brake-side clutch portion transmitting rotational torque from the input side to the output side and interrupting torque reverse-input from the output side (see, for example, Patent Documents 1 and 2).
FIG. 26 is a sectional view of an overall structure of the conventional clutch unit disclosed in Patent Documents 1 and 2, FIG. 27 is a sectional view taken along the line D-D of FIG. 26, and FIG. 28 is a sectional view taken along the line E-E of FIG. 26.
As illustrated in FIGS. 26 and 27, a lever-side clutch portion 111 mainly includes a lever-side outer race 114 serving as an input-side member to which torque is input with lever operation, an inner race 115 serving as a coupling member transmitting the torque from the lever-side outer race 114 to a brake-side clutch portion 112, a plurality of cylindrical rollers 116 serving as engagement elements controlling transmission/interruption of the torque input from the lever-side outer race 114 through engagement/disengagement between the lever-side outer race 114 and the inner race 115, a retainer 117 retaining the cylindrical rollers 116 at predetermined circumferential intervals, a brake-side outer race 123 serving as a stationary-side member restricted in rotation, an inner centering spring 118 serving as a first elastic member which is provided between the retainer 117 and the brake-side outer race 123 and accumulates elastic force with torque input from the lever-side outer race 114, restoring the retainer 117 to the neutral state with the accumulated elastic force through releasing the input torque, and an outer centering spring 119 serving as a second elastic member which is provided between the lever-side outer race 114 and the brake-side outer race 123 and accumulates elastic force with torque input from the lever-side outer race 114, restoring the lever-side outer race 114 to the neutral state with the accumulated elastic force through releasing of the input torque.
In the drawings, reference numeral 113 indicates a lever-side side plate fixed to the lever-side outer race 114 by swaging and constituting the input-side member together with the lever-side outer race 114, and reference numeral 130 denotes a washer mounted to an output shaft 122 through the intermediation of a wave washer 131.
Meanwhile, as illustrated in FIGS. 26 through 28, the brake-side clutch portion 112 mainly includes the brake-side outer race 123 serving as a stationary-side member restricted in rotation, the inner race 115 serving as a coupling member to which torque from the lever-side clutch portion 111 is input, and a plurality of pairs of cylindrical rollers 127 serving as engagement elements arranged in a gap between the brake-side outer race 123 and the output shaft 122, for controlling transmission of torque input from the inner race 115 and interrupting torque reverse-input from the output shaft 122 through engagement/disengagement between the brake-side outer race 123 and the output shaft 122.
A larger diameter portion 115c obtained by enlarging an axial end portion of the inner race 115 functions as a retainer retaining the cylindrical rollers 127 at predetermined circumferential intervals. In the drawings, reference numeral 125 denotes a brake-side side plate fixed to the brake-side outer race 123 by swaging and constituting the stationary-side member together with the brake-side outer race 123, reference numeral 128 denotes a plate spring of, for example, an N-shaped sectional configuration arranged between the cylindrical rollers 127 of each pair, and reference numeral 129 denotes a friction ring serving as a brake member mounted to the brake-side side plate 125.    Patent Document 1: JP 2003-166555 A    Patent Document 2: JP 2003-97605 A